Roasted Samples Research Articles

Effect of Microwaves on Essential Oils of Coriander and Cumin Seeds and on their Antioxidant and Antimicrobial Activities

Coriander (Coriandrum sativum L.) and cumin seeds (Cuminum cyminum L.) were subjected to conventional roasting and microwave heating to study their effects on the volatile components of each spice oil and on both their antioxidant and antimicrobial activities. HD oil of each spice was subjected to GC and GC-MS analysis. A comparison study was done between the two methods of roasting and with raw sample of each spice. Seventeen and sixteen components were identified in essential oils of coriander and cumin seeds respectively. HD oil of raw coriander consisted mainly of linalool (72.7 %) followed by λ-terpinene (8.8 %), α-pinene (5.5 %), camphor (3.7 %), limonene (2.3 %), geranyl acetate (1.9 %) and p-cymene (1.5 %). However HD Oil of raw cumin consisted mainly of cuminaldehyde (26.5 %) followed by λ-terpinene (20.9 %), β-pinene (20.9 %), p-mentha-1,4-dien-7al (12.3 %) p-cymene (7.7%) and p-mentha-1,3-dien-7-al (4.0 %) . In general, the effect of heating on the two spices caused reduction in their essential oil concentrations compared with the raw samples, due to the formation of lipid degradation products, hexanal and (E)-2-hexanal in two treatments. However the sum of their total percentages in microwave treated samples were always smaller than that in conventional roasted samples, which revealed that the microwave heating is more preferable. Moreover, the higher percentage of linalool in microwave heated coriander seeds (57.3 %) than that in conventional roasted coriander seeds (55.5 %) makes the microwave method more preferable due to the fact that linalool increases quality and add fruity and minty aroma to this spice. On the other hand, the total concentration of monoterpenes aldehydes in microwave heated cumin are higher than that in conventional roasting sample (35.7 % and 34.2 %), respectively). These aldehydes contribute to the pleasant characteristic flavour of cumin seeds. Therefore microwave treatment was more retentive of the flavour impact compounds than the conventional roasting treatment and considered the best choice as an alternative-heating medium for processing. Microwaved treated samples showed a remarkable antioxidant activity against DPPH and β-carotene assays, due to the higher concneitation of oxygenated manoterpenes than that in conventional treated samples also for the remarkable percentages of α-pinene, β-pinene, p-cymene and λ-terpinene which may be contribute to the antioxidant activities of both spices, however still lower than that of synthetic antioxidant TBHQ. Both microwave conventionally roasted oils exhibit similar antimicrobial effect against microorganisms under investigation but were higher effect than that of raw oils.

Roasting and packaging in nitrogen atmosphere protect almond var. Guara against lipid oxidation

The effect of packaging in nitrogen (N₂) atmosphere or in air on the quality of peeled and roasted almond var. Guara during storage for 20 weeks at 20 °C ± 1 °C and 65-70% relative humidity (RH) was studied. No changes in the sugar, fat, protein or fiber contents were observed during the storage period nor in color. Only the lipid fraction showed significant changes with the kind of packaging atmosphere. The composition of fatty acids remained unchanged during the 5 month storage in all the samples. Packaging in N₂ atmosphere was seen to have a protective effect against the accumulation of conjugated dienes (CD) in peeled almonds, while in roasted almonds, the protective effect was lower and even nil by the end of storage. The contrary effect was observed for the ultraviolet (UV; K₂₇₀) index which increased more slowly in the roasted samples packaged in N₂, while in peeled samples it reached the same levels at the end of storage regardless of the packaging atmosphere. No effect of the packaging atmosphere was observed on the evolution of the peroxide value in the tested samples (peeled or roasted almonds). None of these changes in the lipid fraction was reflected in the final sensory quality of the samples and the taster panel found no changes in the sensory quality in any case.

Rheological characterization of raw and roasted green gram pastes

Rheological properties of raw and roasted green gram pastes have been determined at different moisture contents (52–56 g/100 g) and temperatures (10–40 °C). These pastes exhibit shear-thinning behavior and possess yield stress. Cross model is suitable (0.986 ≤ r ≤ 0.999, p ≤ 0.01) to explain the flow characteristics of the pastes. The Cross model parameters such as zero-shear viscosity and relaxation time are sensitive to concentration of solids in the paste as well as temperature of measurement, and vary widely between raw and roasted samples. The effect of temperature on the apparent viscosity follows the Arrhenius type relationship (r ≥ 0.961, p ≤ 0.01). The viscoamylographic indices and trypsin inhibitor content are also different for raw and roasted samples. The roasted pastes show a smooth and cohesive microstructure. The optimized sample of roasted flour having a moisture content of 55 g/100 g is suitable as bread spread with appropriate stickiness and spreadability.

Effect of a Traditional Processing Method on the Chemical Composition of Local White Lupin (Lupinus albus L.) Seed in North-Western Ethiopia

The effect of a traditional Ethiopian lupin processing method on the chemical composition of lupin seed samples was studied. Two sampling districts, namely Mecha and Sekela, representing the mid- and high-altitude areas of north-western Ethiopia, respectively, were randomly selected. Different types of traditionally processed and marketed lupin seed samples (raw, roasted, and finished) were collected in six replications from each district. Raw samples are unprocessed, and roasted samples are roasted using firewood. Finished samples are those ready for human consumption as snack. Thousand seed weight for raw and roasted samples within a study district was similar (P > 0.05), but it was lower (P < 0.01) for finished samples compared to raw and roasted samples. The crude fibre content of finished lupin seed sample from Mecha was lower (P < 0.01) than that of raw and roasted samples. However, the different lupin samples from Sekela had similar crude fibre content (P > 0.05). The crude protein and crude fat contents of finished samples within a study district were higher (P < 0.01) than those of raw and roasted samples, respectively. Roasting had no effect on the crude protein content of lupin seed samples. The crude ash content of raw and roasted lupin samples within a study district was higher (P < 0.01) than that of finished lupin samples of the respective study districts. The content of quinolizidine alkaloids of finished lupin samples was lower than that of raw and roasted samples. There was also an interaction effect between location and lupin sample type. The traditional processing method of lupin seeds in Ethiopia has a positive contribution improving the crude protein and crude fat content, and lowering the alkaloid content of the finished product. The study showed the possibility of adopting the traditional processing method to process bitter white lupin for the use as protein supplement in livestock feed in Ethiopia, but further work has to be done on the processing method and animal evaluation.

Transformation of chalcopyrite in the roasting process of copper concentrate in fluidized bed reactor

This work presents the results of investigation process of copper concentrate roasting in fluidized bed reactor with the aim of studying the transformations of copper concentrate minerals as well as to check the accordance with theoretical predictions. The roasted samples were examined using chemical analysis, x-ray diffraction, and mineral microscopy.

Furan Levels in Coffee As Influenced by Species, Roast Degree, and Brewing Procedures

Brazilian green coffee beans of Coffea arabica and Coffea canephora species were roasted to light, medium, and dark roast degrees and analyzed in relation to furan content by using an in-house validated method based on gas chromatography coupled to mass spectrometry preceded by headspace solid-phase microextraction. Furan was not detected in green coffees, whereas levels between 911 and 5852 μg/kg were found in the roasted samples. Higher concentrations were found in Coffea canephora species and darker ground coffees. Some of the potential furan precursors were observed in significant amounts in green coffee, especially sucrose and linoleic acid, but their concentrations could not be correlated to furan formation. Additionally, coffee brews were prepared from roasted ground coffees by using two different procedures, and furan levels in the beverages varied from <10 to 288 μg/kg. The factor that most influenced the furan content in coffee brew was the brewing procedure.

Effect of boiling and roasting on the polyacetylene and polyphenol content of fennel (Foeniculum vulgare) bulb

Fennel (Foeniculum vulgare cv dulce.) is a hardy, perennial, umbelliferous (Apiaceae) plant as a source of the secondary metabolites group's polyacetylenes and polyphenols.The present study investigated the effect of boiling (100° C for 30min) and roasting (160°C for 15min) on the levels of these phytochemicals. Boiling resulted in a significant decrease in the levels of polyacetylenes (falcarinol, falcarindiol, falcarindiol- 3- acetate) and polyphenols (caffeic acid, gallic acid, apigenin-7-o-glucoside, ferulic acid, syringic acid, isovitexin, phloridzin). The loss of polyphenols from the boiled bulbs may be in part due to leaching of these components in the water. Roasting resulted in a significant decrease in falcarindiol, falcarindiol-3-acetate, and falcarinol by 81%, 78%, and 66% when compared to raw unprocessed fennel bulbs. In general, levels of all polyphenols decreased in roasted samples. The exceptions were ferulic acid which showed an increase and gallic acid which did not show any decrease. In line with results for polyphenol levels, antioxidant activity decreased following thermal processing, and the presence of hydroxymethylfurfural was confirmed in roasted samples of fennel.

The Proximate and Functional Properties of African Yam Bean ( Sphenostylis sternocarpa ) Seeds as Affected by Processing

African Yam Bean (Sphenostylis stenocarpa) known as AYB was subjected to different processing treatments such as soaking in water, blanching, cooking and roasting. Soaking was carried out for 24 h. A portion was blanched in hot water at 100oC for 2 min, 4 min, 6 min and 8 min respectively while the last portion was roasted at 100oC for 35 min, 150oC for 30 min and 180oC for 25 min respectively. The samples were then dehulled, dried and milled into flour. The proximate composition and the functional properties were determined for each of the samples. The result showed that the protein content was highest in the control sample (soaked in water for 24 h), while it decreased to 18.82% after 8 min blanching. The decrease was also noticed for the cooked samples to 17.97% for 20 min cooking and 12.53% for 60 min cooking while the roasted samples decreased to 11.55% and 11.33% at the 100oC for 35 min and 180oC for 25 min. The various heat treatments increased the oil absorption capacity from 2.51% to 4.05%; water absorption capacity from 3.76% to 4.68%; swelling index from 4.00 cm to 9.60 cm; bulk density from 0.58 kg/m3 to 0.89 kg/m3. Also, there were decreases in the gelation from 30oC to 20oC; wettability from 9 sec to 1 sec; foam capacity from 29.0 cm3 to 23.3 cm3 and viscosity from 12.30 to 23.3 cp. As a result of these improvements in both the proximate and functional properties of the flour, it could be incorporated in various foods to improve their nutritional value.

Effect of sand roasting and microwave cooking on antioxidant activity of barley

Eight different barley cultivars were roasted in sand and cooked in a microwave oven and evaluated for antioxidant activity (AOA), total phenolic content (TPC), non-enzymatic browning, polyphenol oxidase activity (PPO), total flavonoid content (TFC), reducing power and metal chelating activity. Sand roasting resulted in higher puffing index. Greater increase in yellowness of the roasted flour was brought about by microwave cooking. A significant decrease in TPC (8.5 to 49.6%) and TFC (24.5 to 53.2%) was observed after roasting. The AOA significantly increased (16.8 to 108.2%) after roasting with sand roasted barley exhibiting higher AOA. The reducing power and metal chelating activity significantly increased by up to 77.5% and 78.9%, respectively after roasting with sand roasted samples showing greater effect. The non-enzymatic browning index increased (315 to 774%) and was higher for sand roasted barley. The microwave cooking brought about a greater reduction (45.1 to 76.8%) in PPO activity.

Roasting green coffee beans using spouted bed roaster: changes in physical characteristics.

Pea-berry grade of green coffee (Coffea arabica) beans were roasted in a laboratory model spouted bed roaster at different temperatures (150-250°C) and times (30-300s). The roasted samples were analysed for instrumental colour (hue, chroma and brightness) and texture. Brightness of the roasted samples varied between 5.2 and 20.4%, and time of roasting markedly decreased the brightness values. The chroma showed a curvilinear decrease with both time and temperature of roasting; the lowest values were with highest roasting times and temperatures. The hue or dominant wavelength increased from 576 to 603nm due to roasting. The maximum force offered by the roasted beans decreased with temperature and/or time of roasting. An appropriate condition for spouted bed roasting of green coffee beans was obtained considering colour of samples and desirable low failure/fracture force.

Wheat porridge with soy protein isolate and skimmed milk powder: Rheological, pasting and sensory characteristics

Porridges made from raw and roasted wheat grits ( dalia) with added soy protein isolate (SPI) and skimmed milk powder (SMP) were investigated by employing rheological, pasting and sensory tests in order to develop nutritious products. All porridge samples, irrespective of the presence of SPI/SMP and the application of roasting process, exhibited shear-thinning behaviour, fitted well with Cross equation ( r ⩾ 0.972, p ⩽ 0.01) compared to power law and Casson models. The power indices for porridges prepared from raw grits were higher (0.643–0.764) compared to roasted samples (0.582–0.659). Pasting characteristics like peak viscosity, hot paste viscosity, cold paste viscosity, break down viscosity and total set back viscosity decreased due to incorporation of SPI/SMP. Roasted wheat grits exhibited increased pasting temperature but decreased other pasting characteristics. Pasting temperature increased from 64.4 to a maximum of 74.2 °C due to incorporation of SPI/SMP up to 10%. Porridges made from raw grits along with SPI/SMP had excellent sensory characteristics although roasted grit samples were thinner in consistency and had a better flavour.

Roasting‐Related Changes in Oxidative Stability and Antioxidant Capacity of Apricot Kernel Oil

AbstractApricot kernels were roasted for various lengths of time (0–30 min) at 180 °C and changes in the oxidative stability, antioxidant capacity, color, as well as the level of tocopherols and fatty acids of the apricot kernel oil (AKO) were monitored. While the level of tocopherols decreased, the oxidative stability and antioxidant capacity of AKO increased with roasting, probably due to the formation of antioxidative Maillard reaction products (MRPs) during the roasting. Medium roasted samples (15–20 min) were found to be more resistant to oxidative deterioration. The oil from the 30‐min roasted sample was more susceptible to oxidation compared to the oil from the 20‐min roasted sample in most of the stability tests. Relatively shorter roasting periods (5–10 min) also led to a decrease in oxidative stability in comparison to the unroasted sample. Brownish color and antiradical activity increased with roasting and the highest values were measured in the 30 min roasted sample.

Stress relaxation behaviour of moth bean flour dough: Product characteristics and suitability of model

Stress relaxation characteristics of moth bean (raw and roasted) flour doughs having different moisture contents were determined at two different strain levels (0.05 and 0.50). The decaying relaxation curves for raw flour showed an initial stress between 2 and 22 kPa when the moisture content varied from 28% to 34% at a strain of 0.05. Roasted flour doughs exhibited initial stresses between 0.06 and 2 kPa at moisture contents between 40% and 46%. Dough formation was not possible below 40% moisture content for roasted samples. An increase in moisture content markedly decreased initial and residual stresses. It is desirable that dough should possess a low value of residual stress when used for developing flattened/sheeted products. Models containing two or three parameters were found suitable for large-strain stress relaxation characteristics while low-strain data can be modelled by a 4-element Maxwell model with residual stress.

Innovative methodology for comprehensive utilization of iron ore tailings: Part 1. The recovery of iron from iron ore tailings using magnetic separation after magnetizing roasting

Iron ore tailings have become one kind of the most hazardous solid waste. In order to recycle iron in the tailings, we present a technique using magnetizing roasting process followed by magnetic separation. After analysis of chemical composition and crystalline phase, according to experimental mechanism, the effects of different parameters on recovery efficiency of iron were carried out. The optimum reaction parameters were proposed as the following: ratio of coal: iron ore tailings as 1:100, roasting at 800 °C for 30 min, and milling 15 min of roasted samples. With these optimum parameters, the grade of magnetic concentrate was 61.3% Fe and recovery rate of 88.2%. With this method, a great amount of iron can be reused. In addition, the microstructure and phase transformation of the process of magnetizing roasting were studied.

D-Amino Acids and Computer Vision Image Analysis: A New Tool to Monitor Hazelnuts Roasting?

The roasting process allows complex chemical reactions in foods leading the formation of the Maillard-related compounds, which are of fundamental importance for colour and aroma development in hazelnuts (Corylus avellana L.). Colour is a charming characteristic of roasted foods; despite of their fundamental role in organoleptic properties, the roasting allows accumulation of some potentially toxic technological contaminants, as showed in other matrices (e.g. acrylamide, furan and D-amino acids). Free and protein-bound D-amino acids (D-aa) in foods can origin by technological processing (their formation is pH, time, and temperature-dependent), and also from bacterial racemases in fermented foods, as recently showed in cocoa ( FRIEDMAN 1999; CALIGIANI et al. 2007) So, these compounds can be used as thermal and bacterial markers. Racemisation impairs digestibility/nutritional quality of foods; some D-aa acids are both beneficial and deleterious (DA-WEN SUN 2008). The L*a*b* (international standard for colour measurements adopted by the Commission Internationale d'Eclairage, CIE, 1976) and Red Green Blue (RGB) systems are the most employed methods for colour analysis. Computer Vision Image Analysis (CVIA) coupled with Artificial Intelligence (AI) and related tools (Principal Component Analysis, Artificial Neural Networks, Self Organising Maps) should be considered a powerful approach for evaluating colour development in foods (PATZOLD & BRUCKNER 2006). First aim of our study was to monitor via GC-MS the D-aa formation in hazelnuts during different conditions of roasting. Second aim was to develop a CVIA/AI method to study the colour development in roasted hazelnut, considering the correlation between colour and D-aa too. The racemisation of L-aa (particularly D-aspartic acid plus D-asparagine, D-asx) in hazelnut was time-temperature dependent. Protein-bound D-asx (expressed as D/(L+D); 1.49%) and free D-ala (5.87%) were predominant in Infra-Red roasted samples. Hot-air flow process leads the formation of free-D-aa (D-ala: 6.77%; D-asx: 3.47%; D-glu: 4.50%). Using Back Propagation Neural Network on the Discrete Fourier Transform output (whole surface colour), the identification of hazelnuts samples roasted in different condition was achieved. Red colour decreased according to the correspondent increase of D-amino acids content. Concluding, CVIA/AI is a promising complex tool useful to simplify the comprehension of a complex model system, as colour development in roasted hazelnuts. Keywor

The effect of enzyme systems and processing on the hydrolysis of peanut (Arachis hypogaea L.) protein

Abstract In vitro protein digestion studies were carried out on raw and roasted peanut flour as the starting material in the production of peanut protein hydrolysate. Peanut flour was hydrolyzed with alcalase and alternately in a sequential digestion with pepsin-pancreatin, both for up to 24 h. The degree of hydrolysis (DH) at different times of hydrolysis was determined using the trinitrobenzenesulfonic acid (TNBS) method. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to indicate destruction of native protein units in the enzymatic digests. Hydrolysis with alcalase was very rapid for the first 6 h after which a plateau was reached, whereas that with pepsin–pancreatin was more gradual reaching a plateau after 12 h of hydrolysis. Raw peanut hydrolyzed with alcalase and pepsin–pancreatin had 23% and 21% DH after 24 h respectively, whilst roasted peanut hydrolyzed with alcalase had 21% DH, with the pepsin–pancreatin hydrolysate recording the highest value of 25% after 24 h of hydrolysis. SDS-PAGE results showed that raw peanut samples behaved differently from the roasted samples; increasing hydrolysis time reduced larger peanut protein subunits, with only peptides of

Concentrations of polybrominated diphenyl ethers, hexachlorobenzene and polycyclic aromatic hydrocarbons in various foodstuffs before and after cooking

The cooking-induced changes in the levels of polybrominated diphenyl ethers (PBDEs), hexachlorobenzene (HCB), and 16 polycyclic aromatic hydrocarbons (PAHs) in various foodstuffs were investigated. Foods included fish (sardine, hake and tuna), meat (veal steak, loin of pork, breast and thigh of chicken, and steak and rib of lamb), string bean, potato, rice, and olive oil. For each food item, raw and cooked (fried, grilled, roasted, boiled) samples were analyzed. There were some variations in the concentrations of PBDEs before and after cooking. However, they depended not only on the cooking process, but mainly on the specific food item. The highest HCB concentrations were found in sardine, being lower in cooked samples. All cooking processes enhanced HCB levels in hake, while very scarce differences could be noted in tuna (raw and cooked). In general terms, the highest PAH concentrations were found after frying by being the values especially notable in fish, excepting hake, where the highest total PAH levels corresponded to roasted samples. The results of this study show that, in general, cooking processes are only of a limited value as a means of reducing PBDE, HCB and PAH concentrations in food.

Characteristic Hydrocarbons and 2-Alkylcyclobutanones for Detecting γ-Irradiated Sesame Seeds after Steaming, Roasting, and Oil Extraction

Hydrocarbons and 2-alkylcyclobutanones in sesame seeds ( Sesamum indicum L.) irradiated at 0.5-4 kGy were used to determine the effect of subsequent steaming, roasting, and oil extraction from the roasted samples on the changes in their concentrations. The concentrations of radiation-induced hydrocarbons increased almost linearly (R(2) = 0.8671-0.9953) with the applied dose. The hydrocarbons, 1,7-hexadecadiene and 8-heptadecene, were detected only in the irradiated samples before and after three types of treatments at doses > or =0.5 kGy, but they were not detected in non-irradiated samples before and after treatment. These two hydrocarbons could be used as markers to identify irradiated sesame seeds. The concentrations of the three detected 2-alkylcyclobutanones, 2-dodecylcyclobutanone (2-DCB), 2-tetradecylcyclobutanone (2-TCB), and 2-(5'-tetradecenyl)cyclobutanone (2-TeCB), linearly increased with the irradiation dose. These compounds could be detected at doses > or =0.5 kGy but not in non-irradiated samples. The three types of treatments had no significant effect on the levels of 2-alkylcyclobutanones.

Group-Type and Fingerprint Analysis of Roasted Food Matrices (Coffee and Hazelnut Samples) by Comprehensive Two-Dimensional Gas Chromatography

The present study is focused on the volatile fraction of roasted hazelnut and coffee samples, differing in botanical origins, morphological characteristics, and roasting treatments, selected as challenging matrices. Volatile components, sampled by headspace solid phase microextraction (HS-SPME), were analyzed by GC x GC-qMS, and separation results were adopted to classify, correlate, and/or compare samples and evaluate processing effects. The high-complexity sample profiles were interpreted through different methods: a group-type characterization, a direct fingerprint comparison, and a template matching to extract useful and consistent information, and advantages and limits of each specific approach were critically evaluated. The group-type analysis, focused on several known botanical and technological markers, enabled sample comparison and characterization based on their quali-quantitative distribution; it is highly reliable, because of the authentic standard confirmation, and extends the comparative procedure to trace and minor components. Fingerprint approaches (i.e., direct fingerprint comparison and template matching), on the other hand, extended sample comparisons and correlations to the whole volatiles offering an increased discrimination potential and improved sensitivity due to the wider analyte pattern considered. This study demonstrates the ability of comprehensive GC to further explore the complexity of roasted samples and emphasizes the advantages of, and the need for, a comprehensive and multidisciplinary approach to interpret the increased level of information provided by GC x GC separation in its full complexity.

Detection of γ-Irradiated Sesame Seeds before and after Roasting by Analyzing Photostimulated Luminescence, Thermoluminescence, and Electron Spin Resonance

Sesame seeds were irradiated using a (60)Co irradiator (0-4 kGy) and then roasted (220 degrees C for 10 min). To identify the irradiation treatment, physical detection methods like photostimulated luminescence (PSL), thermoluminescence (TL), and electron spin resonance (ESR) have been investigated before and after roasting. The photon counts of the irradiated samples (nonroasted and roasted) were higher than those of nonirradiated ones, making it possible to distinguish the two samples. The threshold values of nonroasted and roasted samples increased linearly with the irradiation dose, respectively. The TL for the nonirradiated nonroasted and roasted samples presented a lower peak at about 300 degrees C, but irradiated samples showed a higher peak at around 150 degrees C. The areas of TL glow curves were 15 times higher in nonroasted as compared with roasted samples. TL ratio [integrated area of TL 1 (the first glow)/TL 2 (the second glow)] obtained by the reirradiation step was 0 in nonirradiated samples and more than 0.15 in irradiated samples. The radiation-induced ESR signals originating from cellulose were determined in irradiated samples before and after roasting.